Formulation and Evaluation of Almotriptan Malate Nasal Drops

Nasal solutions of almotriptan malate were prepared in phosphate buffer containing different proportions of HPMC E15. In vitro permeation studies were performed using Franz diffusion cell with dialysis membrane and ex vivo permeation studies were carried out using sheep nasal mucosal layer. The formulations were radiolabeled with 99mTc and the nasal residence time was studied in rabbits. Nasal irritation was evaluated in rats. Formulations prepared with HPMC E15 5% w/v did not retard the release of almotriptan. Gamma scintigraphy studies showed increased residence time as compared to plain drug solution. No nasal irritation was observed and the formulations were found stable for 3 months.

Migraine is a chronic debilitating disorder which has been rated by WHO amongst the world's top 20 leading causes of disability.Almotriptan malate (AM) is a second generation triptan which has been shown to have effi cacy comparable to sumatriptan with an improved tolerability profile [1] .Since migraine is spherical particles with corrugated surface (fig.1).Particle size was found to be 4-5 μm (D 50 ).In case of batches A and B TSI data revealed higher fi ne particle fraction (FPF) and dispersibility with the carrier treated with magnesium stearate compared to that obtained with intact carrier and plain microspheres.Carrier treated with 2% magnesium stearate showed better performance than carrier treated with 1% magnesium stearate.With batch C, 1:6 microspheres:carrier ratio did not show any improvement in FPF but with increase in microspheres:carrier ratio to 1:8, significant improvement in FPF was seen (Table 1).Based on TSI study data batch A (intact carrier and 2 % treated carrier), was further taken up for ACI study.Carrier treated with magnesium stearate was observed to decrease the deposition of microspheres on the upper part, especially on the preseperator, and increased deposition was seen on the lower stages compared to the intact carrier (fi g. 2, Table 2).The study reveals the applicability of magnesium stearate as performance improver for catalase microsphere based DPI formulations by covering the high energy binding sites on carrier particles and increasing the dispersibility of microspheres on carrier surface.very often associated with nausea and vomiting there is a need for alternate form of delivery to tablets.Nasal drug delivery is attractive since the large surface area of nasal mucosa affords a rapid onset of therapeutic effect and the potential for direct nose to brain delivery.Liquid delivery either as drops or sprays are very popular with patients due to ease of administration.However the mucociliary clearance results in low bioavailability of the drug via nasal route.Several studies are ongoing to improve the efficiency of bio adhesive polymers for nasal drug delivery [2] .
Nasal solutions were prepared containing AM 8.75 mg/0.2 ml, which is equivalent to almotriptan 6.25 mg.Phosphate buffers were used to maintain the solution in the acceptable range of 4.5-6.5.HPMC E15 was added in different proportions from 2.5-7.5% w/v.The osmolarity was recorded on Osmomat 30.Viscosity of the solutions was recorded using a cone and plate viscometer.In vitro permeation studies were performed using a Franz diffusion cell with dialysis membrane.The receptor compartment contained simulated nasal fl uid (without enzymes) and was maintained at 34±1°.For ex vivo studies same procedure was followed except fresh tissues carefully removed from the nasal cavity of sheep obtained from a local slaughter house were used.The percentage of drug release of optimized formulation of AM was fi tted in various models such as zero order, fi rst order, Higuchi's release kinetics, Korsmeyer-Peppas equation.The formulations were radiolabeled with 99m Tc and administered to rabbits to study the nasal residence time.Nasal irritation study was done on rats to observe tissue irritation to the nasal mucosa after administration of the formulation.The formulations were subjected to stability studies at 25 0 , 30 0 /65 % RH and 40 0 /75% RH.

RESULTS AND DISCUSSION
The pH of the formulation was kept at 4.5 since the ideal range is 4.5-6.5.The osmolarity of the solution was found to be 405.Viscosity was found to be in the range 0.159-1.818poise.An antimigraine drug is In the past, the intramuscular and oral administrations of vaccines were considered the ultimate ways.Intranasal vaccination is a viable alternative, because it most often resembles better the natural way of infections, self administration is easily done and therefore may gain a reasonable share within the next couple of years.

ADVANTAGES OF INTRANASAL VACCINATION
For most microbes, the nasal mucosa is the fi rst barrier which must be conquered.So it's not a surprise, that this mucosa is very immune-competent.It was shown, that even small amounts of antigen elicit a protective response.This will become a striking argument, if the poor yields with the current H1N1 vaccine seed strains and the workload linked to virus production in eggs are considered.It is also a clear advantage, that nasal vaccination induces both mucosal (protection at site of infection) and systemic immunity.In contrast, intramuscular vaccination primarily induces systemic immune response (antibody formation).In addition, intranasal vaccination may confer protection against infections at other mucosal sites, such as the lungs, intestines and genital tract, and provide cross-protection expected to provide immediate relief to the patient.Mucoadhesives used should not retard the release of the drug.It was observed that formulations prepared with HPMC E15 5% w/v did not retard the release of AM.The release mechanism from the hydrophilic polymers was decided by the "n" value obtained by fi tting the data in Korsmeyer-Peppas equation.Gamma scintigraphy studies showed increased residence time as compared to plain drug solution.The nasal tissue showed normal upper respiratory epithelium from cuboidal to columnar appearance.No abnormalities were detected.Formulations were found to be stable up to 3M under accelerated conditions.A further investigation is required to detect the blood and brain levels achieved.AM nasal delivery is a promising alternative to tablets in the treatment of migraine.

Fig. 2 :Fig. 1 :
Fig. 2: Histopathology of rat nasal mucosa Histopathology of rat nasal mucosa in haematoxylin-eosin stain.A. control sample and B. treated sample A B